Abstract

We studied the electronic structure of a conventional superconductor, ZrB12, using high resolution x-ray photoemission spectroscopy and single crystalline samples. Experimental results with different bulk sensitivity reveal boron deficiency at the surface while the bulk is stoichiometric and different valence states of Zr at the surface relative to those in the bulk. Signature of satellite features is observed in the Zr core level spectra corresponding to the bulk of the material suggesting importance of electron correlation among the conduction electrons in the bulk while the surface appears to be uncorrelated. These results provide an insight on surface-bulk differences, which is important for fabrication of devices based on such superconductors.

Received 10 July 2013Accepted 18 July 2013Published online 02 August 2013

Acknowledgments:

The authors acknowledge financial support from the DST-DESY project to perform the experiments at P09 beamline at PETRA III, Hamburg, Germany and Dr. Indranil Sarkar for his help during the measurements. The authors, K.M. and N.S. acknowledge the Department of Science and Technology for financial assistance under the Swarnajayanti Fellowship Programme. G.B. wishes to acknowledge financial support from EPSRC, UK (EP/I007210/1).

Abstract

We studied the electronic structure of a conventional superconductor, ZrB12, using high resolution x-ray photoemission spectroscopy and single crystalline samples. Experimental results with different bulk sensitivity reveal boron deficiency at the surface while the bulk is stoichiometric and different valence states of Zr at the surface relative to those in the bulk. Signature of satellite features is observed in the Zr core level spectra corresponding to the bulk of the material suggesting importance of electron correlation among the conduction electrons in the bulk while the surface appears to be uncorrelated. These results provide an insight on surface-bulk differences, which is important for fabrication of devices based on such superconductors.